The invention relates to a steering wheel of a motor vehicle having a display unit that is disposed in the steering wheel rim and, in the manner of a scaled display, provides the driver of the vehicle with an indication of the vehicle steering angle. Alternately, the present invention can also be described by a method for displaying a variable related to the steering angle of a motor vehicle in the form of a scalar display on the rim of a steering wheel of the vehicle. With respect to the prior art, reference is made to DE 10 2011 112 134 as well as DE 10 2009 059 670 A1.
The basic principle of highly automated driving, also referred to as autonomous driving, where a two-track, not track-bound motor vehicle is operated in public road traffic solely by an electronics unit, is comprehensively known at least to those skilled in the art. Taking into account suitable current data from the surroundings of the vehicle, the vehicle is not only braked or accelerated, but also steered to at least follow the course of the road. Ideally, the steering wheel should be decoupled from the steering train by suitable modes of action and remain in its neutral position even when negotiating curves, which is to say, it should not rotate during automatic steering of the vehicle.
In this context, it is known from DE 10 2011 112 134 that an operating property, which also refers to an autonomous driving mode, is displayed to the driver of the vehicle via a light source disposed in the steering wheel rim. The DE 10 2009 059 670 A1 reference describes a steering wheel of an industrial vehicle via which the steering angle change speed is specified so that the current position of the steering wheel does not allow any conclusions as to the wheel steering angle, which is why said wheel steering angle is displayed via electroluminescent diodes on the steering wheel rim in the manner of a scalar display.
In particular, in a prolonged introductory phase of systems that facilitate autonomous driving (in the following, this will be the only term used, even for the so-called highly automated driving) in motor vehicles, in particular in sedans, it will be difficult for the drivers of such vehicles to blindly trust said systems to take correct action. In particular, during the state of autonomous driving when the steering wheel is stationary, a driver knows very little about the current steering angle of the vehicle; this is because he can derive said steering angle only from the movement of the vehicle, with said vehicle moving either on a track specified by the course of the road, or it can also, to a certain extent, deviate from the course of the road. Depending on the driving speed, the driver may also feel the vehicle steering angle as a result of the centrifugal force. For the sake of completeness, it should also be mentioned in this context that the term “vehicle steering angle” describes in the present case the angle between the longitudinal axis of the vehicle when driving straight ahead and the longitudinal axis of the vehicle when the vehicle negotiates curves; however, such a steering angle can also represent the so-called current “mean” steering angle of the steered vehicle wheels.
The object of the present invention is then to counteract the driver's uncertainty during autonomous driving mode, which was described in the preceding paragraph. The object of the invention is attained in accordance with embodiments of the invention.
According to the invention, when a motor vehicle moves autonomously or in a highly automated fashion, a variable (suitably) related to the steering angle (the vehicle steering angle or the mean steering angle of the steered wheels) is displayed to the driver in the manner of a scalar display on the rim of the vehicle's steering wheel, which steering wheel does not move when negotiating curvy roads. Thus, the driver receives useful and reassuring information about a correctly functioning steering system since the displayed steering angle variable is going to change during the vehicle's drive in correlation with other information that signals a steering movement of the vehicle to the driver. The present invention is described above in the form of a method, as well as a steering wheel device.
On a steering wheel according to the invention having a display that is provided in the steering wheel rim and that gives the driver of the vehicle an indication, in the manner of a scalar display, with respect to the vehicle steering angle, the display can be advantageously refined such that the display operates in a slightly anticipatory manner and therefore gives the driver an indication of the vehicle steering angle to be set by a control system for the autonomous driving mode on a stretch of road that lies ahead and is visible to the driver. The display is active at least when the motor vehicle is in the autonomous or highly automated driving mode in which the steering wheel does not move, not even when the vehicle negotiates curves. A method according to the invention can work accordingly, which is to say, the driver is effectively provided with a steering angle preview for a stretch of the road that lies ahead and is visible to the driver. This is possible in a simple manner because a control system for autonomous driving has all of the information required to initiate, in a timely manner, the actions required for the driving task coming up.
Furthermore, it may be provided that at least in certain boundary conditions, the display according to the invention displays the vehicle steering angle either too great or too small. In particular during fast driving on the autobahn, only curves with very low curvature have to be negotiated, which requires very low steering angles. So as to render such low steering angles or steering angle changes visible at all, they should be displayed in an exaggerated or enlarged fashion. On the other hand, for example when parking the vehicle and thus at very low driving speeds, the resulting steering angles are so high that they suitably should be displayed in a reduced fashion because otherwise, the quickly changing display could irritate the driver. According to the description above, the size or the intensity of the increase or decrease of the displayed vehicle steering angle therefore may depend on the driving speed of the vehicle.
As regards the design of the display as such, there are various design options; however, the preferred design is any type of scalar display such that a higher value to be displayed runs in the displayed form over a larger segment of the steering wheel rim than a smaller value to be displayed. It goes without saying that the steering direction should also be suitably displayed so that, for example proceeding from the highest top point of the steering wheel in neutral position, the scalar display travels to the right when negotiating a right curve, and to the left when negotiating a left curve. The current steering angle (or a lower or higher steering angle that would be required to display the current steering angle), can always be displayed by emphasizing in color or brightness the appropriate segment on the steering wheel rim to display in this way to the driver the steering movement on the steering wheel (which is actually not moving). Ideally, the display segment does not take up the complete width or depth of the rim, but rather requires only on a narrow ring on the steering wheel rim. Of the ring, only a respective relevant segment is emphasized in some manner. It goes without saying that the respective display can also be suitably prepared in an additional form, for example damped, with higher-frequency, quasi “nervous” portions of the steering angle being filtered out.
A display as described above, for example a display ring provided in some fashion on the steering wheel rim, on which according to the invention a variable related to the steering angle is represented visually in the manner of a scalar display, can also be used for additional displays for the driver. In particular in dangerous situations related to the steering task, the need for manually interfering can be pointed out to the driver; at the same time, he can be given recommendations for a favorable intervention, such as, for example with various colors, brightness, type and frequency of running patterns, and much more. Even when, during autonomous driving mode, it becomes necessary for the driver to take over the steering task, a request to that effect can be made via, or supported by, optical signals (such as blinking, movement patterns, etc.) of the aforementioned display ring.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.